1. Field of the Invention
The invention relates generally to vascular catheters, and in particular to improved vascular catheters having guide wire lumens which terminate through the catheter body.
Atherosclerosis is a common human ailment arising from deposition of fatty-like substances, referred to as atheroma, or plaque, on the walls of blood vessels. Such deposits occur within the peripheral blood vessels, which feed the limbs of the body, and the coronary vessel, which feed the heart. When deposits accumulate in localized regions of blood vessels, narrowing of the vascular lumen, referred to as stenosis, occurs. Blood flow is restricted and the person's health is at serious risk.
Numerous approaches for opening such stenosed regions are known. Of particular interest to the present invention are approaches which introduce diagnostic or therapeutic devices into the vascular anatomy through a guiding catheter or a sheath. Insertion of guiding catheters into the heart is described generally in U.S. Pat. No. 5,163,921, the disclosure of which is herein incorporated by reference. Briefly, guiding catheters are typically inserted into the femoral artery in the groin and advanced towards the heart. The guiding catheter is then directed through the patient's aorta until the distal tip of the guiding catheter reaches the ostium of one of the coronary arteries. Once the guiding catheter is placed in the ostium, various therapeutic or diagnostic devices can be inserted through the guiding catheter and into the coronary artery.
In order to introduce the various devices beyond the distal end of the guiding catheter, a guide wire is commonly employed. The guide wire is introduced into the vascular anatomy through the guiding catheter where a distal end of the guide wire is advanced past a distal end of the guiding catheter and into the coronary artery. With the guide wire in place, a diagnostic or therapeutic catheter can be advanced over the guide wire and into the area of interest. Diagnostic or therapeutic catheters of interest include a lumen for receiving the guidewire so that the catheters can be advanced over the guide wire in a manner often referred to as "tracking".
Of particular interest to the present invention are catheters or sheaths where the guide wire lumen terminates through the body of the catheter or sheath between a proximal and a distal end. Unlike previous catheter designs (often referred to as "over the wire" catheters) wherein the guide wire lumen extends the entire length of the catheter body, these catheters have a guide wire lumen which extends only over a portion of the catheter body.
One particular catheter design of interest where the guide wire lumen does not extend the full length of the catheter shaft is the "rapid exchange" catheter design. In rapid exchange catheters, the guide wire exits the catheter shaft at some point near the distal end of the catheter and the remaining length of the guide wire runs alongside the catheter shaft until both the catheter and the guide wire exit the patient.
Two rapid exchange catheter designs which are of particular interest to the present invention are long lumen rapid exchange designs and short lumen rapid exchange designs (the latter sometimes being referred to as "monorail" designs). In the case of long lumen rapid exchange catheters, the side port through which the guide wire exits will typically be 10 cm or more from the distal tip of the catheter. In a particular type of long lumen rapid exchange catheter, referred to as a common lumen rapid exchange catheter (described generally in U.S. Pat. No. 5,203,338, the disclosure of which is herein incorporated by reference), the catheter body includes a working lumen in addition to the guide wire lumen. These two lumens are disposed in a proximal region of the catheter and are in communication with a common lumen at a distal region of the catheter. When inserting the common lumen catheter into a patient, the guide wire is introduced through the common lumen and advanced into the guide wire lumen. The relatively long engagement of the guide wire with the common lumen and the guide wire lumen allows the distal end of the catheter to more easily be passed through tortuous of the regions of the vascular anatomy, i.e. provides good trackability. Once the catheter is in the desired region of the vascular anatomy, the guide wire can be withdrawn from the vessel and stored in the guide wire lumen just proximal to the common lumen. A diagnostic or therapeutic device can then be advanced from the working lumen and into the common lumen without being obstructed by the guide wire.
A particular diagnostic device which is of interest to the present invention is an ultrasonic imaging core that can be advanced form the working lumen and into the common lumen to produce an image concerning the extent and nature of the stenotic material in the vessel. The ultrasonic imaging core will often include an imaging transducer or reflective element mounted on a rotatable drive shaft disposed within a flexible catheter body. The transducer, reflective element, or both, can be rotated within the catheter body to direct an ultrasonic signal generally outward in order to scan the interior of the blood vessel wall.
Short lumen rapid exchange catheter designs generally employ a much shorter guide wire lumen at the distal end of the catheter, typically in the range from about 1 cm to 4 cm. Unlike the long lumen rapid exchange catheters, the guide wire lumen is disposed entirely within the distal region of the catheter body. The short lumen rapid exchange catheter further includes a central lumen extending from a proximal end and terminates near the guide wire lumen. Once the short lumen rapid exchange catheter is positioned within the artery, an interventional, imaging, or diagnostic component of the catheter can be advanced through the access lumen and up to the guide wire lumen.
Other catheters or sheaths having a guide wire lumen which terminates through the catheter body include "convertible tip" catheters and sheaths as described generally in copending U.S. patent application Ser. No. 08/292,864 (Attorney Docket No. 12553-47), filed Jul. 29, 1994, the disclosure of which is herein incorporated by reference, and "rapid exchange delivery catheters" as described generally in copending U.S. patent application Ser. No. 08/271,878 (Attorney Docket No. 12553-48), filed Jul. 7, 1994, the disclosure of which is herein incorporated by reference.
The termination of the guide wire lumen through the side of the catheter body presents particular problems not generally associated with catheters where the guide wire lumen extends the entire length of the catheter body. One particular problem is the transitioning of the exit of the guide wire from the catheter body and into the guiding catheter. As the guide wire exits laterally outward through the catheter body, it is desired to have the guide wire gently redirected toward the catheter body so that the guide wire can run alongside the catheter body without kinking or producing an excessive amount of friction with the catheter body, both of which can reduce trackability.
A particular problem experienced with short lumen rapid exchange catheter designs is buckling or prolapse of the guide wire when the catheter is removed from the vessel. Buckling or prolapse of the guide wire when removing the catheter from the patient can cause serious inconvenience and can be time consuming for a surgeon removing the catheter.
In some common lumen rapid exchange catheter designs, the proximal region of the catheter has an asymmetrical cross section. Such an asymmetrical configuration reduces the catheter profile so that the guide wire can more easily run alongside the catheter as it exits the patient. When the guide wire exits such catheters, it is preferred to have the guide wire follow a single side of the catheter body. One problem experienced with such designs, however, is the spiraling of the guide wire around the catheter body which effectively increases the profile of the catheter and reduces trackability.
It would therefore be desirable to provide catheters and sheaths which improve trackability and reduce the possibility of having the guide wire buckling or prolapse. In the case of asymmetrical catheter designs, it would further be desirable to provide a catheter body wherein the guide wire can exit the catheter body and travel along a single side of the catheter body until exiting the patient.
2. Description of the Background Art
Vascular ultrasonic imaging catheters having rapid exchange designs are described in U.S. Pat. Nos. 5,201,316; 5,204,234; and 4,951,677. Catheter sheaths having guide wire side ports near the distal ends are described in U.S. Pat. Nos. 4,932,413; 4,824,435; and 4,552,554. A short lumen rapid exchange balloon dilation catheter is described in U.S. Pat. No. 4,762,129. An ultrasonic imaging catheter having a common distal lumen is described in U.S. Pat. No. 5,203,338. A catheter having two lumens in a proximal region and a single lumen in a distal region is described in U.S. Pat. No. 5,219,335. A catheter having a guide wire lumen with a slidable sleeve is described in PCT International Application No. PCT/US93/07323 and PCT/US93/07217.